Recovery of abietic acid in the form of its quarter salt



Patented Jan. 10, 1950 RECOVERY OF ABIETIC ACID IN THE FORM OF ITS QUARTER SALT Frederick H. Gayer, Chicago, Ill., assignor to Continental Research Corp., Chicago Heights, 111., a corporation of Illinois No Drawing. Application May 3, 1947, Serial No. 745,723

21 Claims. (Cl. 260-4975) This invention relates to a process for obtaining resin acids of the abietic acid type in the form of their quarter salt.

In one specific embodiment the present invention relates to a process for separating resin acids of the abietic acid type in the form of their quarter salt, from resin acid mixtures of sizable abietic acid content and originating from various species of coniferous trees, such as rosin, tall oil resin acids, and the like starting materials as hereinafter more fully described.

It is well known that rosin contains two main types of resin acids: 1

(1) Primary resin acids which include "sapinic acids, l-pimaric and d-pimaric acids.

(2) Abietic acids, the most important individual member of which is l-abietic acid.

The primary acids are the acids produced by the living tree. With the exception of d-pimaric acid they are highly unstable compounds and are isomerized into abietic acids by heating to relatively moderate temperatures, b catalytic agents such as mineral acids, glacial acetic acid or by ultra-violet light. The isomerization apparently proceeds by stages, each stage corresponding to individual acids intermediate between. the unstable primary acids and the relatively stable final product of isomerization, viz. l-abietic acid. The isomerized acids are isomorphous and by fractional crystallization only a partial resolution of their mixtures can be effected. It is for this reason that in the technical literature the isomerized acids are usually referred to simply as abietic acid which is to be understood as a generic term rather than one implying a chemical individual. It is in this sense that the term will be used herein. A stricter characterization of what constitutes abietic acid according to the present disclosure is found in the ability of l-abietic acid and the more highly isomerized acids to form an acid alkali metal salt of the composition the so-called quarter salt, while the primary acids and possibly the less isomerized acids lack this ability. The quarter salt has a strong tendency to crystallize from organic solvent solutions and has therefore been used for the isolation of abietic acid from other rosin compounds. The term abietic acid, as used herein, is therefore further defined as denoting those components of rosin which are capable of crystallizing in the form of the quarter salt.

According to the isomerizing influences to which rosin issubjected before and during its 5 processing, the abietic acid content of different samples of rosin is subject to wide variations.

Generally speaking, the gum rosin contains less abietic acid than wood rosin. Rosin treated either by heating or by chemical means to increase the proportion of abietic acid is known as isomerized rosin, one form of which is Commercial Abietic Acid. A highly isomerized rosin is available inthe resin acid fraction of tall oil, the abietic acid content of which is Well over A common characteristic of the resin acid mixtures enumerated above is that if they are relatively free of oxidized rosin they will undergo crystallization if kept for prolonged periods at temperatures ranging from approximately to C. The tendency to crystallization sharply increases with the abietic acid content of the resin acid mixture and is incomparably stronger with tall oil resin acids than with gum or wood rosin.

An object of the present invention is the separation of abietic acid material, that is, abietic acid in the form of said quarter salt which may subsequently be decomposed to abietic acid, from-the other types of resin acids which do not form a quarter salt and will be simply termed nonabietic acids or non-abietic type resin acids. In contrast to the starting materials and to the separated abietic acid material fraction, the nonabietic acid portion is characterized by the absence of crystallizability when kept for prolonged periods at higher temperatures. The non-abietic acid fraction therefore constitutes non-crystallizing rosin which is highly useful in the arts Wherever crystallization during the heating of v rosin is disadvantageous and the separation and recovery thereof is another object of my invention.

While rosin owes much of its traditional usefulness to the properties resulting from its complex composition, a successful method for separating its components as to chemical type may be of great value for future developments. Each type of resin acid can be assumed to be more useful for special purposes than its mixtures with other types. Besides having increased usefulness in some of the known commercial applications, such separated resin acids may find use as starting materials for synthetic products. Despite the obvious advantages involved, however, prior art relating to the separating, on a commercial scale.

of resin acids of one type from those of another is practically non-existent. In known instances of the prior art of obtaining abietic acid, organic solvents are used as; c'rystallizing media. According to some of these methods, the abietic acid is separated in the form of its quarter salt which, due to its low solubility in organic solvents, can be obtained in the crystalline form in a higher yield than abietio acid itself. However, the use of organic solvents makes all previousl used methods 5 unattractive.

According to the present invention and in distinction from the prior art, the quarter salt of abietic acid is obtained by using water as the. crystallizing medium. A necessaryconditionfor the formation of a crystalline producta asidis closed herein, is a minute subdivision and uniform distribution, briefly;a dispersion ofvresin acids in water which, besides acting as a:dispersing medium for the resin acids, also contains acertain minimum proportion of resin acidxsoap -in solution. I have found that in aqueous :dispersions of resin acid mixtures in which at least one fourth of the resin acids are neutralized-with an alkali metal base, on standing, especially at some v What -elwaited-temperatures, the: quarter I salt of e'abie'tic acid will crystallize; and- -th'at under favorab1e' cOhditiOnS' it is-pOssi-bl eZ-to precipitate-"substaiitially all i of: the abietic acid present in the form ofits crystallinequarter'salt 'whilethenon- "abi'e'tic type resin acids-remain in the" dispersion. By separating: the crystals from the aqueous "-phase; as 'byfi-ltration, quartersalt is i obtained i from whi'ch a'bietioacid of high purity can herecovered; -the filtrate containing all of thenonabietic' type-resin acids originally present in the starting material; 1 r a l The-following examples areintrocluced toiillustratdmportantfeatures ofithe presentinvention.

,,Example' 1 I '1 Ten; gramsN'woodrosin, acidnumber-1-63; were aheatedeiunder reflux with 8.9- cc:v 2.135;:Nrsodium .shydroxide to neutralize 65% .of :the resinsacids.

"whilestir'ring wascontinued, cc? 2N sulphuric acid-were added which caused decomposition ,of

one-half ofmthe soap previously formed. fiThe milky dispersiomwhich nowcontained 65% of the resin acids as dispersed-free resin acids and'35% as-soap was allowed to stand several" hours at about-'80? C. The crystals formed'were separated byfiltration. I

rystalline product.'6.0 grams quarter salt, 'acid number 130. Dissolving' the quarter-salt in benz'ol,-refiuxing'thesolution with a slightexce'ss of hydrochloric acid; washing and evaporation of the benzol gave abietic acid; acid number 180.

The filtratefromthe crystalswas acidified and "the liberated-acids recovered. The recovered mixture-was a soft solid at room temperature since-it contained'themajor portion of the neu- '-"trali matter" originally-}present. "In .orderto re- 'movelthe neutral -bo'di'es the *mi'xture'= was neu- "tralized with 2.04 N sodiumhydroxide andthe neutral matter extracted with benzol. Decomposition of the extracted soap gave hard resin acids, acid number 173 and a melting point higher than that of the isomerized rosin. These resin acids are non-crystallizing when kept at elevated temperatures and do not form a quarter "salt.

Ezramplet Ten grams of a tall oil resin acid fraction, acid "number 175, were reacted With 11.0 co. 2.135 N e sodium hydIOXide:;to neutralize-75% of the resin ,GBJCidSiPIGSEHt. The mixture was stirred into 250 ..cc, boilingwatenand stirring continued while 7.8

.,-lcc.,f2;N ,sulphuridacid were added to decompose stwo thirds,otgtheisoap formed. The dispersion was allowed to crystallize while it cooled to room i temper'ature.

'Grystalline product-5.3 grams quarter salt, asidmumber 135.

These examples strikingly illustrate the simplicity and economy ofi'the presentprocessinDb- ...,tainingithe quarter salt as comparedtothemethods of the previous art which,werebasedyon the use,,of.;.o.1'sanic solvents. It is "easily seen;- how eyenpithat, as to, results, crystallization from aqueous, dispersion is "fully equivalent "to "crystallizationlirom, organic solvent s'c lutions,' i. e: the quarter salt crystallizes from, a medium which it- .--.self retains the non 'abi'etic typet'resin, acids and I'theneutral bodies. Indeed;,crystallization'from dispersion according togthe presentinvention,

.mightbe looked upon as a-partial,; irrever sible and oriented" flocculation which afiects pnly the ,abietio, acid portion of..the dispersed phase. in other words, the dispersions; underlying the present, process are highly unstable as, i-regardsl the abietic acidportiom but stable as'to ;the nonabietic .acid portion "of the dispersed phase. *Q'Ifhis Q difierence, in stability makesxa: clean separation -.-Ihe mixtureswas'rstirreddnto:460,:ccszhot watc -14c oft-he twQitypjes-rof' resin acids-possible 1 The, most important 'characteristiciof the-"dispersionsiuseful in accordance with the-present invention, is, the proportion of, free-resin acids jtototal resina'cidspresentjn the dispersion in Examples I l, 2 and 3' the proportions ;0f=-free resin agc'ids'were ,35'%,;65% and"75.%, respectively,

the balance consisting; ofresin acid soap; j'Itis easily seenfthat the: function of the, resin ac'id soap, at least'that'portion-of the soap which is ,"alkali abietate, is "more, than that; of a" dispersing agentgsince theg alkali :abietate enters-into .the crystal structureyofqthe quarter salt. to he .ratio of: free resin acids togresin' acid soap, "the, present-disclosure islimited to a ratio of "3: l ,or less. In distinction, my co-pending application;1Serial,No: 745,721,,describes a-methodfor obtainingprystalline abietic acid from dispersionsin whichthe'above ratio is higherthan 351. ;The boundary betweenthe crystallization of abi- ;etic-acid and ,of,quarter salt is not sharp-one 6U- and-there may exist a narrow rangeof free resin acidzresin acid soap ratios in which both abietic acid ,and=--tthee-quarter salt;,crystallize. It also will be realized that with difierent starting materials the" dividing ratio may vary; somewhat 65 ahdallowa-nce must 'a lsoj be-made fcrsuclriac-tors as the proportion of water to solids in' the dispersions, the nature and theconcentration or the salt present, the cation "Off the soap; details of manipulation,- etc. i I In'the border region-betweenquarter salt and abietie acid crystals,':-the-type of crystal is espe- -ci-ally sensitive-tothe effectpf hydrolysis of the dissolved alkali abietate. -Tl usffactors --favor ing-'- hydrolysis *suchas -low; -soap concentration (htgh water ratiol favor-the: formationof abietic separation might be rather incomplete;

" acid crystals, whereas influences which repress hydrolysis, such as presence of salt, shift crystallization toward the quarter salt side.

' The proportion of free resin acids in a crystallizing dispersion is' most conveniently expressed as the percentage proportion of free resin acids related to the total of free and neutralized resin acids present and will herein be termed "free resin acid ratio, abbreviated: FRA. Expressed in this form, dispersions in accordance with the" presentinvention are of a free resin acid ratio of'fromabout to 75%, the yield ofquarter salt increasing as the free resin acid ratio increases. 7 acid ratio of 65% gives a yield of quarter salt sufficiently high to result in a satisfactory sepa- As shown by Example 2, a free resin ration of the abietic from the non-abietic" type resin acids.

I will now describe in detail the starting materials used, and individual process steps, such as methods for obtaining the required FRA ratio and for creating dispersions, the effect of the concentration of the dispersed phase of salt concentration and of temperature, and other factors entering into the present process.

' Starting materiaZs.Starting materials for the present process may be gum rosin, wood rosin, isomerized rosin or tall oil resin acids, or, in general, resin acid mixtures of sizable abietic acid content and originating from various species of.

coniferous trees. Preferably the starting materials should contain a minimum' of oxidized material, the presence of which is liable to slow down crystallization of the abietic acid fraction. If the object is to obtain the quarter salt in the highest possible yield, starting materials of low abietic acid content may be given a previous isomerizing treatment.

' Tall oil resin acid starting materials are avail- I able in 'a number of different forms. Tall oils as such, especially distilled or chemically refined or partially esterified tall oils are suitable starting 'materials. However, the yields of crystalline resin acids obtainable according to the present invention directly from tall oils are generally low because of the presence of a large proportion of ifattyfacids; The latter, even in the neutralized or otherwise modified state, have a tendency to prevent crystallization of the abietic acid-frac tion. For this reason, I prefer as starting materials tall oil resin acid concentrates. These may originate from any of the known processes for separating tall oil into its main components,

namely fatty and resin acids, even though such While some of the separation processes produce resin acids which for all practical purposes are free of fatty acids, the resin acid fraction from other processes might still contain minor portions of the fatty acid fractions, either modified or free I fatty acids, originally present in tall oil.. I have found that such tall oil resin acids can be efficiently processed according to the present invention. Since the fatty acids are stronger acids than the resin acids, decomposition of the resin acid soaps precedes that of the fatty acid soaps. Consequently, the fatty acids remain dissolved as soaps in the aqueous medium containing the non-crystallizing, non-abietic acid portion of the resin acids and are therefore completely sepa-- rated from the crystalline quarter salt portion. A few examples of tall oil resin acids especially useful as starting materials for the present process y way of illustration and not-lirhitation are:

. (1 The resin acid fractionobtainedin the dis- 5 tillation of tall oil or modified (for example, partially esterified) tall oil by removing the major part of the fatty acids first, the resin acidfraction either coming over as a higher boiling distillate or remaining as still residue; (2) resin acid fractions originating from one of the numerous selective solvent processes for separating tall oil; (3) the dilute resin acid soap solution obtained according to Patent No. 2,356,988 and originating from a partial separation of fatty acid esters form a modified tall oil in which the fatty acids are present as alkyl esters;

(4) the impure crystalline resin acids which separate from crude or distilled or chemically refined or partially modified tall oils on standing and still contain a minor portion of the non-abietic type resin acids and of the fatty acids originally present; (5) resin acid fractions furnished by a group of tall oil separation processes based on modifying the fatty acids, neutralizing the resin acids and removing the fatty acid component from the neutralized resin acids, etc. A typical example of these processes is that of Patent No. 2,348,9'l0to Gayer and Fawkes which is based on esterifying 'the fatty acids, neutralizing the resin acidsto obtain water-soluble soaps and removing the 'flfatty acid" component by solvent extraction.

" These processes result in a resin acid soap solution which keep dissolved a portion of the exj"'t racting solvent. After removing the major portion of the solvent such resin acid soap solutions can be directly processed according to the present invention.

' All the aforementioned starting materials contain diverse proportions of non-abietic type resin acids. However, the presence of non-abietic acids 'is' not a necessary condition for obtaining the quarter salt according to the general principle of the present invention. Abietic acid, devoid of non-abietic type acids and obtained either by conventional methods or inaccordance with the process disclosed in my co-pending application,

"Serial No. 745,721, can be transformed into the I quarte'r'salt by the process disclosed herein. That is, the quarter salt will crystallize from dispersions'which contain abietic acid of a free resin acid ratio of from about 10% to 25%. Vice versa abietic acid can be prepared by the process of the aforementioned co-pending application by using 'the quarter salt as a starting material and increasing the FRA ratio to more than 75%. Considering the great simplicity and economy of the *present process, as compared with methods involving the use of orlganic solvents, the purely preparative step of obtaining the quarter salt from crystalline abietic acid must be considered anotherobject of the present invention.

- Mixtures of two or more of any of the aforementioned starting materials can be used.

FRA ratio and the preparation of dispersions.- The FHA ratio indispcrsions underlying the pres: ent invention may range from approximately 10 to It is obvious that for efiicient operation such FRA ratios will be preferred as will result in maximum yields of the quarter salt and there- 'by insure maximum separation of the abietic acid vpersion of a partially neutralized1rosin;;by;s mple :yie d any desined fii su ab e. S Ja'QQQ- n tedafre 3 r7 .-,ti9n.=.m yba esomn sedlw wra h b l e tina it wi h a i persion ma mad l hea. er aimFR' t qeand hls ubseai nt l s oeit anihieh rlor i o a d onal d e mn s ipnlspan- Thuswh 't ezmax mn ie d f Quarter a esubs que stepzin rea e the fre tr n qi ra :rtutherane ivin max mum. e -f' lhea e en ei fis ep lis. zh pi l-iniohtai in a'r pp ldisp rsimt g aw eniusing oder te a ita o nBesides applyin a i ation v-oreus di sin machines (colloid; mills, ghomogenizers) ---example,-lp fl w-neut aliz d r qd SSOIVE in a-smiallnuanti yzof; u .esol-yent; such as alcohol and the'solution s; into suitable quantities of water All jgmethodsvcan be, varied,,,.a ;oor1 i i; ng;to. one on the :-:.other:of the several modif gations known 3115-1 3 elpersion technology ,Forexample; I; may d sperse a. mixture of free resin. acids andresin yacid soaps -:--in water or diSpCISErIESiH acids in a soapsolption, .1101?:disperse-resinacids in-a-suitable zg ntit of water. containing; sufficient alkali 1:0 ;p11Qd1, l0e ;1Zhe; 4 e required I quantity of soap.

A. combination :of dispersing methods also-. may .be employed. For example, I. may ,crea dis agitation andrthen runithe dispersion-throu h. a. 4:1 dispersing or; homogenizing;;maehine tosohta n. a s'finer dispersion. 5 Or Ilm'ay partiall 1 the resin acidsv with. aportionmf; alkalimorresponding to-thefinal FRA ratio ,l and:.+soluhilize s all lornpart. for the balance :of': the resin; acids with iammonia ill.:OiEdBI'- to obtain. a'soap-or ameasi-ly idispersible free resin .acideresin .ac-id .soap-an-ixture,-z then drive :ofli the ammonia ands-thereby e disperse the resin acids; liberatedeby the remoyal L-With Water to decrease its solids..;content,=' OIrr-tWO dispersions. oi a:- different; FRAAt-atio may. .beloom sbinedin such proportions that the :resultingrzdispersionswill be of" the .desiredFRA ratiol From "the foregoing, it must be; evidentthataflllarge number c-fvariations are possible ineprod-uc-ing' a "certain FRA ratio or creating suitable .dispersions nd,-.therefore, the-present:inventions-is :not mited to or: depend ent upon. any. particular :fatifi -;or creating. a dispersion. "siInigen'eral,

s L. prefer creatinga.crystallizingw.dispersiom:si-

=-emethod-. .or.- sequence of stepsain; establishingeancm ,the proportion ofi free, resin acids to resin agid elfiga p V The proportion of water to the resin aoid starte n smateri l: i z.-of:ctons dera le; mporta n 0' --prenari-ng t e dispersions? Th s proportion to be med-1, wa nvr ti'oflkis. defined asxpar swby .ei -ht pf-lwat r to o zpartoi starting material, hedatter-including; notionlyfree and neutralized T-IeS D- 'QidS'b tLQJSO:n b d S and impuritie 5 The dispersions underlying'thegpresent proeess are-of theoilinewater type. -As iS kl'10W.1'l,;t-0. ob- ;.;-tain suchdispersions ofresin .;acids,, the-.;water as to-be present inroonsiderable excess .overzrthe otal qyresino-us; matter. "If,2;f0r iexam'ple; insane -part, :of. rosin-,-'65% of the resin acids are; neu- Jralized zby-y. gently. heating; it under --refluxi.t;with the oalculatedramount of 2- Nssodium hydroxide, l; a water-in-oil type dispersionresults. Orr-slow :additiomofabout fiyeipartsmf hot Water; the quar- 5;. terasaltmay begin to; crystallize beforereversion 'ofthesphases-takesq1place..: :Such crystallization is.;not withinv the scope *of: the :present invention.

If, instead, the samemqnantityaof hot. water=;is.

N added-rapidly reversal -of.;phases takes place and o -a ...:.=.0il,-in-water-' type =..zdispersion is formedbewfore erystallizationlsets-in. In general, the formation {of oil-in-waten type dispersions of resin aeids-requires. a. minimumwater ratioyoflfrom about 5 1170 10,:dependingon the ERA ration-To gobtain easily;filtrable dispersions-the waterratio -sh,ould beat least from about 10 to 720; M'y..preferred: limits are awwater ratiorof fromyaboutmo t b ut- 50. Nariations within; these limits "are substantially lwithouteffect on the results.

Anotherpfaotori influencing the preparation :of dispersionsis the; presence of salt dis'solvedin H he aqueous 1;v ha,se.: Such salt may originate-from ,7 the deoompositionreaction,;between resin-acid oapand'mineral .acidin adjusting the free Tresin {preparing the dispersion, err-may he in-tro(1uced' by thewater, used, or maybe conained; i the;startingamaterial; as, for example, saltedoutresinacidsoap fraction. 'There is a ertain maximum saItmOncentration below which rc :rflQ gQiSDGISiOIlS :are "easily .made: and crystallization proc eeds.--smoothly 'resulting in Well -deVeIOpEd crystals. --When the ,salt concentration exceeds the; maximum limit; dispersion becomes diflicult and a portion ofithematerial to be dispersed=may reoipitated in the -resinous form, or. aportion the soammay be-salted out. -Maximum---:-salt =--gozreentrations-for sodium'sulphate, for example, nrare'xof the order -.of 1.5150 2.0% with respect to the awatenpresent. Byusing a sufficiently high water ;.=least,-' completely water-soluble resin .aoid soap-e70 ratio 'impreparing' or diluting the dispersions; the

-With acid because with, this method satisfactory egdispersionscan: be made with a mmimum aof mechanical --work and--simple equi ment.

-- -theart' that-while -tlrie-results-olzvtainableaeeoillas romiianipi .-.::;sa1tconeentrationvcan be conveniently reduced inelow;' the rn-torimtun-:concentration. 'If thesalt is' sod ium -sulphate or sodium ehloride," I prefer wto w rk a eqngen ati s r ab ut W310. les

e,in the -foregoingflxample 2*the decomposition of the sodium resinate with 5.2 cc. 2 N sulphuric acid caused the formation of 0.74 grams sodium sulphate which, dissolved in 250 cc. water gives a salt concentration of approximately 0.3%.

Temperature-Of considerable importance for a successful operation of the present process is the temperature at which the dispersions are prepared and at which crystallization is allowed to proceed. I have found that both process steps can be carried out at a temperature range of from approximately normal room temperature to the boiling point of Water. However, within the preferred ranges of FRA ratios, I prefer to work within a temperature range of from approximately 35 C. to 100 C. because in this range dispersions are easier made and crystallization takes place more rapidly than near room temperature. Thus, I found that dispersions made at higher temperatures from gum or wood rosin, or, in general, from rosins which have not been given an isomerizing treatment, if rapidly cooled to near room temperature, Will not form any crystals at all or, at best, crystallize extremely slowly. Even at higher temperatures such dispersions frequently require stimulation by seeding or agitation to bring about crystallization. Variations as to temperature are possible inasmuch as preparing the dispersions and crystallizing them can be done at different temperatures.

Processing chemicals-The alkaline agents most likely to be used in commercial operation for neutralizing resin acids are sodium carbonate or sodium hydroxide. Other alkaline sodium compounds can be used for neutralization. Potassium is fully equivalent with sodium as it also forms the quarter salt. Mixtures of several alkaline neutralizing substances can be used. For partial decomposition of resin acid soaps a number of acids, organic or inorganic, or acid salts like sodium bisulphate can be used. For plant scale work I prefer sulphuric acid suitably diluted. It is immaterial whether the acid is added to a suitably diluted soap solution or whether a soap solution is poured into water containing the requisite amounts of acid. Carbon dioxide, if cheaply available, can be used to obtain dispersions giving quarter salt crystals.

Time required for crystallization-4 have found that the time required for complete crystallization varies widely with different starting materials, crystallization being the more rapid the higher the degree of isomerization of the starting material. Dispersions made from highly isomerized resin acid mixtures develop crystals spontaneously, starting within a few minutes after the dispersion is made and complete crystallization of the quarter saltis especially rapid.

The rate of crystallization is of an entirely different order in dispersions made from rosins of a low degree of isomerization such as gum rosin. Such dispersions crystallize very slowly. Crystallization can be stimulated by seeding, agitation, alternate cooling and heating. A homogenizing treatment also may initiate and accelerate crystallization. Normally, crystallization is complete in from about one to several hours. At FHA ratios resulting in maximum yields, the needleshaped crystals of the quarter salt arrange themselves in the form of a stiff meshwork. The crystals are filtered and washed with water until the soap reaction of the wash water becomes negative.

10 Crystal size and crystal forms-A necessary condition for efficient filtration is that the crystals be well developed and oi a suinciently large size. The rate of crystallization and correspondingly the size of crystals are conveniently controlled by the water ratio, higher ratios, i. e. lower concentration of the dispersed phase favoring slow crystallization and the formation of large crystals. While easily filtrable crystals may be so small as to appear crystalline only under magnification, under favorable conditions the quarter salt crystals reach linear dimensions of 1-2 mm.

Thecrystal form assumed by the quarter salt obtained according to the present process is the same as that obtained in organic solvent solutions, i. e. thin needles.

Products-The crystalline products obtained according to the present invention are characterized by a purity much greater than that of the starting materials. While the acid number of the quarter salt obtained according to the examples is subject to rather wide variations, the average acid number of the abietic acid obtained by decomposing the quarter salt is about '180. Since the acid number of most starting materials ranges from about 160 to 1'70, thehigh acid number of the separated abietic aid portion indicates that a large part of neutral bodies of the starting material remains dispersed with the non-abietictype acids. The colorof the abietic acid fraction also shows a great improvement over that of darkcolored starting materials. It is apparent that if applied to highly isomerized starting materials as, for example, tall oil resin acids, the present process is a highly efiicient refining process since the bulk of the starting material is recovered in a high state of purity, the minor portion, consisting of non-abietic acids, neutral bodies and coloring matter, remaining in dispersion.

In commercial practice the quarter salt, if not used as such, may be decomposed to abietic acid by dissolvingthe quarter salt in a hydrocarbon solvent and treating the solution with a dilute mineral acid. In the alternative, the major portion of the quarter salt can be transformed into abietic acid in accordance with the procedure of my aforementioned co-pending application, as previously indicated herein. That is, using the quarter salt as starting material a dispersion is made, the FHA ratio increased to between and by decomposing it with mineral acid,

7 and abietic acid is allowed to crystallize by permitting the dispersion to stand at 'a temperature 'of from room temperature to 100 C.

Thejnon-a'bietic acid portion remaining in the filtrates from the crystalline quarter salt portion can be utilized in several ways. The filtrate from the quarter salt contains a minor portion of free resin acids and in appearance ranges from a clear soap solution to an opaque dispersion. One application of such dispersions may be their direct use as paper size. After neutralizing the free resin acids the filtrates also may be used for preparing metallic 'resinates. The solids content of the filtrates can also be recovered by decomposing the soap present and, if necessary, accelerating the coagulation of the free acid by heating or adding salt. Or the solids content of the filtrates maybe salted out and the resulting resin acid-resin acid soap mixture further processed. The separation-of the free resin acids from the acidified aqueous phase is greatly aided by the use of hydrocarbon solvents. The resulting solutions canbe subjected to well-known refining -p messes roam-pitt 'the*co1orfand"dec'r""sethe hlitrallbqdy Cohtefitbf thejdissdllled 'acids. "Q'rsuch resin acidsolutions' 'can undergbchemioal processing such as chlorination, sulphonation,

12 aciddisperslons'ar given' in the following'fltable. It was observe'dthat uptd a" FRA ratio-M 75 %"'the crystals were -needle hapedrwhereas 1at*80'%-=the characteristic plates of abietioacidwere obtained.

Isomerized N Wood Rosin, I Tall Oil Resin Acids, Acid H t f v Acid No.165 "N0.'170 P t- 1 ercen- "ra i r Y p I Yield, Acid 525i? Yield I Acid I Q H 2%;? pm. patient No percent percent N0 percent lization i 25 f 6 134 I 0.09 8.7 0.5 I I 15 134 0.17 r 8.5 ,25 30 4 128 0 25 40 134 0.26. v 8.4 40 25' 46 r 120 o 35 50 138 0.34 8.3 =50 .25 54 Y 136 I. 0.43 v 8.2 .00 l ,25 1 49 127 0. s0 57 130 1 0. 52 8.2 '65 25 51 128 0454 eo 138 0.50 ..70 .25 56 120 0.58 01 137 0.00 8.1 .25 59 131 0.62 02 139 0.65 8.0 8.5 -25 00 180 0. e0 03 180 0. 09 7.7 8.2

Abie'tic acid. etc. Due to its high :content of neutral matter Example 5 which usuallyhasthe' consistency 'of'asoft solid or of a viscous liquid; the non abietic acid'por'tion 'recoveredfrom the'filtrate is,'"a's a rule, soft and tacky; By' removing the 'neu'tr'al bodies-*nonabietic type resinaci'ds of a'satis'factory acid num- 1591' and p ointare'obtained. Such removal of the--neutral* matter can be efiected by neutralizing the resin ac'idcontent with an alkali metal base such sodium hydroxide, regulating the concentration of the soap solution .to provide more than 30 "grams of neutralized-resin acids per 100 grams of soap 'solutiong 'and extracting the neutral bodies with a solvent such as hydrocarbon solventr Application 'of thisprocss to the nonaibietic acid fraction is, due to 'the high neutral body content of-the latter, much moreeconomical than extracting the neutral matter from the starting material. I

' 'In{ contrast to the abietic acidfraction; the recovered non-*abietictype acids-are,- even when freed-0f the major portion of neutral matter; noncrystallizing when kept for prolonged periods at temperatures ranging from their melting :point to about 150 C. The resin; acids obtai-ned by removing, the major portion orthe neutral bodies fromthe non-abietic acid portion have higher melting points than the'fre sin acid mixture-from which they "originate: Thus, the melting points of,N wood rosin and isomerized N wo'od rosin, as used in Examples 1";and 2 respectively, were 80 and 82 C. respectively. The non-abietic acid portions freed from neutral-bodies had 'melting points of and 93 C; respectively. Thefcombination of high meltingpoint and lack of Crystal- 'liz'ability are novel featuresjheretoiore not found 'in any of the so-called non-crystallizing rosins.

The following examples illustrate the present fprocess in its most important phases, such as the efiect of the FRA ratio, use of'difierent starting materials, and some of the numerous variations in procedure for obtaining dispersions of a certain FRA ratio.

Example 4 Samples of neutral soap solutions of isomer ized N'wood rosin and oftall oil resin acids, which 'werediluted' with distilledwater to a water ratio ratio increasing with each sample; The resulting dispersions were "allowed to crystallize 'at' a'itemperature 'of"60 C. Yields" and "acid'numb'e'rs of the "crystalline quarter salt; calculated salt con-'- cent'rations and pH values for the-wan oil 'r'e'sin Tengrams Commercial Abietic Acid, acid number 171, were neutralized with aqueous sodium hydroxide and the soap solution diluted to 400 cc. The solution was heated to 90 C.and 40% of the soap decomposed with dilute sulphuric acid. The dispersion --was allowed to crystallize at 80 ;C. for two hours. r H

Crys talline p'roduct. 4.3 grams "quarter salt, acid number 127.

Example 6 Five grams isomerized'N wood rosinwerere- Example 7 larly neutralizedanddiluted as in Example 6. To the hot solution were added 2.5 cc. of. an aqueous sulphur dioxide solution which titrated 2.2 N using plienol'p'hthale'inas indicator." The resulting dispersion wasorysta11ized'at75" C.

' Cry'stallinej product-=23 grams quartensalt, acid'numb'e'r 129.

. Exdiiip le 8 Five" grams tall oil resiri acids; 1 acid number 175,

were refluxed with 1.95 cd. .4'.'0potassium"hydioxide to neutralize 58% -01 the resirracidsl The mixturewas incorporated into ccfboiling water with vigorous stirring.- Almost immediately quarter salt began tocrystallize.

. Crystalline product-3.0- .grams .-quarter-salt, acid number 126.

Example 9 Ten grams isomerized'N v/o od' rosinwre reacted with sufficient sodium hydroxide to neutra1ize"4(% of the resin'a'cid's. The 'i'nixtur ewas transferred "into 250 cct'warmwater containing sufficient ammonia to eauseeenia t solution of 1 the mixture; The soap solution-washer boiled until the odor of ammonia disappeared. There- Fivegrams isomerized N wood rosin were simi- 13 sulting' dispersion was allowed 'tocr-ys'tallize at about 80 C.

Crystalline product-53 grams quarter salt, acid number 129.

On removing the solvent from a resin acid soap rafllnate resulting from the tall 011 separation process according to Patent No. 2,348,970, an acid sodium resinate was obtained which had thefollowing composition: Sodium acid resinate containing 35% free resin acids, 64.5%; water, 30.3% sodium sulphate, 5.3%.

191 grams of this mixture were stirred into 2600 cc. boiling water. The FRA ratio was adjusted to 60% by adding sulphuric acid. At this point, the sodium sulphate concentration of the aqueous phase of the dispersion was calculatedas 0.6% The dispersion was allowed to crystallize and then filtered.

Crystalline product-64.5 grams quarter salt, acid number 131. I

A portion of the quarter salt was transformed into abietic acid according to the procedure of the co-pending application, Serial No. 745,721. The abietic acid obtained had an acid number of 183 and a specific rotation of -45.

Example 11 A crude tall oil was rapidly distilled at a pressure of 13 mm. until the distillate was 55% by weight of the charge. The still residue had an acid number of 129 and the composition, 50.6% resin acids, 22.1% fatty acids and 27.3% un-' saponifiable.

Ten grams of the still residue were completely neutralized with sodium hydroxide, the soap stirred into 300 cc. boiling water and sulphuric. acid added to decompose 65% of the resin acid soap. The resulting dispersion was allowed to crystallize for several hours.

Crystalline product-29 grams quarter salt, acid number 131.

Example 12 Twenty grams crude resin acid crystals separated by centrifuging crystallized crude tall oil and containing 20% fatty acids were :heated with 2.31 N sodium hydroxide to neutralize all the fatty and resin acids present. The soap solution was diluted with 600 cc. hot water and dilute. sulphuric acid added in an amount equivalent to 75% of the resin acids present. The dispersion was allowed to stand until a solid meshwork of crystals formed.

Crystalline product-40.8 grams quarter salt, acid number 130.

Example 13 One hundred cubic centimeters of a resin acid soap solution obtained by the tall oil separation process according to Patent No. 2,356,988 and containing 8.3 grams resin acids and 2.3 grams fatty acid esters plus unsaponifiable were diluted.

The solution was heated to Example 14 In a mixture of grams isomerized N wood rosin and 10 grams crystalline resin acids obtained by separation from a crystallized crude tall oil in which the fatty acids were esterified,

80% of the acidity was neutralized by refluxing with 2 N sodium hydroxide and the hot mixture stirred into 1 liter boiling water. The FRA ratio was now increased to 70% by the addition of 2 N sulphuric acid and the resulting dispersion allowed to crystallize while cooling slowly to room temperature.

Crystalline prodnct.11.7 grams quarter salt, acid number 135.

. 1 Example 15 Ten grams abietic acid obtained according to the process of my co-pending application, Serial No. 745,721, were completely neutralized with sodium hydroxide and the volume of the soap solution made up to 300 cc. The solution was now heated to near the boiling point and 70% of the soap decomposed with sulphuric acid. The quarter salt crystallized rapidly,

Crystalline product-8.0 grams quarter salt, acid number 135.

I claim as my invention:

1. The method of recovering abietic acid from mixed resin acid material of the group, consisting of rosin, isomerized rosin, tall oil resin acids and their mixture, and alkali metal soaps of said materials, which comprises preparing an aqueous dispersion containing said resin acid material in partially neutralized condition at a free resin acids ratio in the range of from 10% to 75% and in from 10 to 50 parts by weight of water, and crystallizing abietic acid therefrom in the form of its quarter salt by permitting the dispersion to stand at a temperature of from about normal room temperature to about C.

2. The method of separating mixed resin acid material of the group consisting of rosin, isomerized rosin, tall oil resin acids and their mixtures and alkali metal soaps of said materials into crystalline abietie acid material and noncrystallizing non-abietic acid material fractions, which comprises preparing an aqueous dispersion containing said mixed resin acid material in a condition of from 25% to 60% alkali neutralization and in from 10 to 50 parts by weight of water, crystallizing abietic acid therefrom in the form of its quarter salt by permitting the dispersion to stand at a temperature of from about normal room temperature'to about 100 C., and separating the resulting crystalline material from the aqueous medium, the latter containing the nonabietic type resin acids.

3. The process of claim 2 wherein the non-abietic type resin acids are separated from neutral matter contained in said aqueous medium and re-' covered as a separate product of the process.

- 4. The process of effected by neutralizing the resin acid content with an aqueous solution of an alkali metal base while regulating the concentration of the resulting soap solution to provide more than 30 grams of neutralized resin acids per 100 grams of soap solution, and extractin the neutral bodies therefrom with a hydrocarbon solvent.

5. The method of separatin mixed resin acid material of the group consisting of rosin, isomerized rosin, tall oil resin acids and their mixtures and alkali metal soaps of said materials into =crys-" talline abietic acid material and non-crystallizing non-abietic acid material fractions, which comprises preparing an aqueous dispersion containing said mixed resin acid material in a condition of partial neutralization regulated to a free resin acids ratio of from 10% to 75% and infrom 10 to 50 parts by weight of water to provide a pH of from about 9.5 to about 8.0, crystallizing abieticacidtherefrom in th form of its quarter claim 3 wherein separation is I5. salt: by p rmitting the dispersion to stand at :a temperature; of from about. 35. C. to about-1100. C.,1and..separating the resulting crystalline. ma: terial from the aqueous phase. 6. The method of separating abietic-acid from: mixed resin acid material of the groupconsiste ingof rosin, isomerized rosin, tall oilresin acids and their mixtures, which comprisespreparing. an aqueous dispersion containing said resin acid material in a partially neutralized conditional; anapproximately 75% free resin acid content and in from to 50 parts by weight of water, and. crystallizin abietic acid material therefrom in the form of a mixture of abietic acid andits quarter salt by permitting the dispersion to stand at .a temperature of from about C. to about. 100C. I 7 The method of separatingabietic acid from mixed resin acid material of the group consisting of alkali neutralized rosin, isomerized rosin,..tall oil resin acids and their mixtures,-which comprises. preparing an aqueous .dispersion..contain.-.,.

ing said material regulated to a free resin acids ration of from 10% to 75% in fromv 10 .to 50 parts by weight of water to form an oil-in-water type dispersion and to reduce .concentration of alkali metal salt content below 2%, and crystal, lizing abietic acid therefrom .in the form of its. quarter salt by permitting the dispersion to stand at a temperature of from about 35C. to about 100 C.

8. The method of separating .abietic acid from? 7 mixed resin acid materialof the group consistingv of rosin, isomerized rosin, tall oil resin acids and theirnmixtures and alkali metal soapsof said. mixtures, which comprises preparing anaqueous. dispersion containing said material. in partially neutralized condition at a free resin acids. ratio. of from about to 75% and in from 10 .to 50 parts by weight of water, andcrystallizing the, abietic acid therefrom predominantly. in the. form of its quarter salt by permitting the-.dispersionto stand. at a temperature of from about 35". C. to. about 100 C.

The process of recovering abietic acid from mixed resin acid material of the group consist-r ing of rosin, isomerized rosin, tall oilresin .acids; and their mixtures, which comprises neutralize ingsaid material with an. aqueous alkali, agitate ing and diluting the soapsolution with. added water to providea water to solidsratio .of approximately 20-50 to 1 and. to reduce concen.- tration of salt subsequently formed in the proc-L ess below. about 1%, decomposing the soap. with an acidicmaterial until from 10% t0 75% of the.

resin acids are in the free state, andcrystallizing the abietic acid therefrom in the form of its quarI-H ter salt by permitting the dispersion to .standat a temperature of from about 35- cpto about 100 C.

10. The process of claim .9 wherein the alkali is an alkali metal hydroxide.

- 11. The process of claim 9 wherein the acidic material is' sulfuric acid. 12. The process of claim 9 wherein the :resin. acid material-is wood rosin.

. 13. The process of claim 9 wherein theresinacid material is isomerized rosin. H 14. The. process of-claim 9 wherein the-resin acid material is tall oil resin acids. 15. The process of separating abietic acid from. aqueous solutions of the alkali metal soaps-of mixed resin acid material of the group consisting of-rosin,-isomerized rosin, tall :oil resin acids and ir...m 2 t re ,.-.wh comprises. as tatii gsend 15' from'in the form of its-quarter salt by permitting 16; dilutingtthessoap solution with water to provide a water to solids ratio of approximately. 20-50. to ..=1::and to reduce concentration of alkali'metal salts formed in the process below about-1%, (deecomposing the soap with an acidic material until from 10% to 75% of the resin acids are in the free state, and crystallizi'ng the abietic acid therethediSpersion to stand; at a temperature of from about 35C. to about 100C.

16. The process of separating abietic'acid from aqueous solutions of the alkali metal soaps of mixed resin acid material of the group consist ing'of rosin, isomerized rosin, tall oil resin acids and theirunixtures, which comprises diluting the soap solution with water to form a water to solids ratio'of approximately 20-50 to 1, saturating-the soap with carbon dioxide to provide a free resin acids ratio in the range of from 10% to 75%, and crystallizing the abietic acid therefrom in the form of-its quarter salt by permittin thedispersion to stand at a temperature of from about- 35-'C. to about 100 C.

17. The process of separating mixed resin acid material of the group consisting of rosin, isomerized rosin; tall oil resin acids and their mixtures into abietic acid and non abietic portions, which comprises neutralizing from 25% to 60% of the free resin acidcontent of said material with an alkalLand dispersing it in from 10 to parts by weight of water, thereafter permitting the dispersionto stand at a temperature of from about 35 C. .to'j'about 100 C. until abietic acid in the form or its quarter salt crystallizes therefrom; and separating the crystalline material from. the aqueous medium, the latter containing a mixture of non-abietic'type resin acids and neutral mat; ter;

\ 1 8. Theprocess of separatingabietic acid conev tained in mixed resin acid material of the group consisting of rosin, isomerized rosin, tall oil. resin acids and their mixtures, which comprises neu-, tralizing from 25% to of the free resin acid content of said material with an alkali, incorporating it in from 10 to 50 parts by weight of water ands'olubilizing the remaining free resin acid content therein with ammonia heatingthem-ix turerto drive off the ammonia and thereby dis persing the resin acids liberated by'removal of the ammonia'andcrystallizing abietic acid therefr0m=in the form of its'quarter salt by permitting" the dispersion to stand at a temperature of from about35 C. to about 100 C.

19. The method of separating abietic acid-froi" mixed resin acid material of the group consisting of rosin, isomerized rosin, tall oil resin acidsand their mixtures,-which comprises preparing an aqueous dispersion containing said material in partially neutralized condition .at a free resin. acids ratio ,of from. about 40% to and'in from 10.to .50 .parts by' weight'of water by first neutralizing the free resin acids in excessof said ratio and-then decomposin them. to said ratio,-

and crystallizing abietic acid therefrom in the form of its quarter salt bypermitting the dis-. persionto stand at a temperature of from about n'ormalroom temperature to about C.

"20. The process of obtaining the quarter salt. of abietic acid fromcrystalline abietic acid, which comprises neutralizing said crystalline material with. anaqueous alkali, agitatingand diluting: the soap solution .with added water to provide a waterto solids ratio'of approximately 20-50 to .1 and toreduce concentration-of salt subsequently formed int-he EPIKOQeSSJbBIOW about 1%, decomposing the 18 REFERENCES CITED The following references are of record in the file of this patent:

Palkin et al.: J. A. C. 8., vol. 55, pp. 3679-3680 

1. THE METHOD OF RECOVERING ABIETIC ACID FROM MIXED RESIN ACID MATERIAL OF THE GROUP, CONSISTING OF ROSIN, ISOMERIZED ROSIN, TALL OIL RESIN ACIDS AND THEIR MIXTURE, AND ALKALI METAL SOAPS OF SAID MATERIALS, WHICH COMPRISES PREPARING AN AQUEOUS DIEPERSION CONTAINING SAID RESIN ACID MATERIAL IN PARTIALLY NEUTRALIZED CONDITION AT A FREE RESIN ACIDS RATIO IN THE RANGE OF FROM 10% TO 75% AND IN FROM 10 TO 50 PARTS BY WEIGHT OF WATER, AND CRYSTALLIZING ABIETIC ACID THEREFROM IN THE FORM OF ITS QUARTER SALT BY PERMITTING THE DISPERSION TO STAND AT A TEMPERATURE OF FROM ABOUT NORMAL ROOM TEMPERATURE TO ABOUT 100*C. 